使用Linq to Entities 3.5选择空列 [英] Using Linq to Entities 3.5 to select null columns

问题描述

我正在使用实体框架3.5 。我的模型有一个Mediator表和一个MediatorAvailabilities表。大多数Mediator没有MediatorAvailabilities（Availability = Null）中的条目，但是我仍然需要带回调解器，无论是否存在相关的MediatorAvailabilities。

I am using Entity Framework 3.5. My model has a Mediator table and a MediatorAvailabilities table. Most Mediators do not have an entry in MediatorAvailabilities (Availability = Null) but I still need to bring back the mediator whether or not there is a related MediatorAvailabilities.

下面的我的查询只有在有相关的可用性时才带回中介。再次，如果可用性= null，我如何得到调解员：

My query below is only bring back a mediator if there is a related Availability. Again how do I get mediators even if Availability = null?:

Dim mediators = (From m In entity.Mediators.Include("MediatorAvailabilities") _
Where(m.MediatorAvailabilities.Any(Function(a) a.Availability = String.Empty Or a.Availability.Contains("Weekends") = True))
                         Where (m.isActive = True) _
                        Order By m.Sequence _
                        Select New RankingCriteria() With { _
                            .FirstName = m.FirstName, _
                            .LastName = m.LastName, _
                            .CompanyName = m.CompanyName, _
                            .PhoneHome = m.PhoneHome, _
                            .PhoneWork = m.PhoneWork, _
                            .PhoneMobile = m.PhoneMobile, _
                            .Email = m.Email _
                        }).ToList()

d的正确方法是什么？这个？

What's the correct way to do this?

推荐答案

我想你需要添加 a.Availability是Nothing 在任何方法调用如下：

I think you need to add a.Availability is Nothing in your Any method call like so:

Where(m.MediatorAvailabilities.Any(Function(a) a.Availability is Nothing Or a.Availability = String.Empty Or a.Availability.Contains("Weekends") = True))

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